Antenna



Jan. 30, 1945. THOMAS ETAL- 2,368,174

ANTENNA Filed Aug. v12, 1942 @DCDQ a 1NVENTOR 52am 5 Ag Patented Jan.30, 1945 ANTENNA Charles W. Thomas, Wayne, and William A. Robinson,Detroit, Mich, assignors to Ford Motor Company, Dearborn, Mich., acorporation of Delaware ApplicationAugust 12, 1942, Serial No. 454,566

1 Claim.

This invention relates to radio equipment; and, more particularly, to anantenna designed to be attached to a motor car or other mobile objectfor the transmission of radio signals.

This invention concerns a transmitting antenna which may be used onautomobiles, boats or aircraft in connection with the transmission ofshort wave radio signals. To permit mobility and avoid damage onphysical interference with outside objects, these antennas are generallyin what is known as the whip form. That is to say, a strong, flexiblerod or relatively small diameter is mounted vertically on the vehicleand supported thereon at its base. The length of this rod is usuallytaken, for reasons well known to those engaged in the art, as onequarter .01? the length of the wave of the signal to be transmitted overthe antenna since this gives the maximum output eiiiciency.

The whip antenna, when proportioned according to formula is usuallyupwards of six feet in length and when installed on any of the availableplaces of mounting on the vehicle necessarily projects a considerabledistance above the top of the vehicle. While operating in open country,this is not undesirable but when the vehicle is used on roads withoverhanging trees or under viaducts or in entering and leaving garages,sheds, etc., the antenna will strike these outside objects and while itsinherent flexibility prevents its destruction it is subject to damageand interference with the signals being transmitted. This defect hasbeen recognized in the past and telescopic or pivoted antennas developedbut neither of these is suitable for transmission purposes.

Therefore an object of this invention is to devise a means by which awhip antenna may be selectively secured in a position in which operatingefficiency is insured and yet the antenna is not subject to interferencewith outside objects. It is a further object of this invention to devisean antenna which may be secured in a plurality of different positionswith respect to the vehicle upon which it is mounted to obtain differentelevational clearances and yet maintain the operating efficiency of theantenna throughout.

Other advantages will be apparent from the following description of thedevice itself and the method of application.

With these and other objects in view, the invention consists in thearrangement, construc tion and combination of the various parts of theimproved device as described in the specification,

claimed in the claim and illustrated in the accompanying drawing inwhich:

Figure l is an elevation of a motor vehicle upon which the antenna ismounted.

Figure 2 is an elevation on an enlarged scale of the retaining device.

Figure 3 is a section through Figure 2 taken on the line 3-3 thereof.

Referring to Figure 1, theantenna 1:0 is shown installed on a motorvehicle ll, the lower end of the antenna being fixedly secured in aninsulator l2 traversing the body wall adjacent the top of the fender andbraced by astirhup bracket l3 also insulatingly fixed on the body of thecar above the insulator l2. The antenna 10 is the conventional whip typein the form of a flexible rod of small diameter and has a 'ball 14formed at its upper end. So far, this represents the con.- ventionalstructure and mounting used with this type of radio equipment.

The normal position of the antenna is shown in dotted outline in Figure1 in which it extends vertically above the car. The alternative positionshown in full line is that used when the antenna would be subject tointerference from outside objects and it is held in this position by aretainer 15 which is shown in greater detail in Figures 2 and 3.

As shown in these figures, the retainer it comprises a base [6,preferably made of metal, and which has a hook l'l formed thereon whichis engaged in the drip mold 18 of the automobile. This maybe done byengaging the tip of the hook H in the mold [8 while holdin the retainerhorizontally, erecting the retainer and deforming the mold to secure theretainer permanently. The top H! is made of insulating material, in thiscase Lucite or an equivalent and is rigidly secured to lower portion byscrews 20. A slot 'l, having ball end 22 i formed in the top 19 and asinstalled on the vehicle, the slot is directed rearwardly and upwardlylongitudinally of the vehicle II and inwardly and upwardly transverselythereof. A slot of this configuration will receive .the ball tip 14 anda portion of the antenna it which may be snapped into it, and maintainit in position shown in full line in Figure l, the resiliency of thewhip antenna being a sufficient locking means.

The advantage of this construction over the conventional telescopic orpivoted antennas is that the operating characteristics of this antennaare not appreciably disturbed by being sprung down as long as there isno decrease in its actual length. Thus, though the field strength may bedecreased slightly due to the lower elevation of the antenna in its downposition, tests have shown that this results in an audible signaldiminution of less than 3 decibels at a distance of 20 miles with theusual motor vehicle transmitter equipment when the bow in the antenna issemicircular or less. This is inconsequential in so far as practicaloperation is concerned and is far superior to the results obtained withantennas which must be pivoted or telescoped to obtain necessary roadclearance. Th former-in the lengths requiredare cumbersome and unwieldlyand the points of application to the vehicle are limited. The latter, ofcourse, require an actual decrease in the effective length of theantenna giving less efllcient characteristics.

Another advantage is the fact that the antenna may be released from theretainer when operating in clear country to obtain maximum fieldstrength; and this is done by merely pulling the antenna slightlyforward and outwardly, disengaging it from the retainer-merely thereverse of the procedure by which it is inserted and held therein. Thesimplicity of this device and its arrangement may be readily understoodfrom the drawing. Its use of an existing structural portion of the carfor its attachment requires no disfiguring or mutilation of the car bodyitself. Furthermore, it consists of but two simple parts (or these maybe made integral if that is desired) and ofiers an extremely economicalconstruction. Heretofore various expedients have been tried to obtainthe necessary road clearance and still maintain an operating conditionof the antenna but none has been particularly satisfactory. Certainlynone has had the simplicity and economy of the device which is heredisclosed and claimed.

Some changes may be made in the arrangement, construction andcombination of various parts of the improved device without departingfrom the spirit of the invention and it is the intention to cover by theclaim such changes as may reasonably be included within the scopethereof.

The invention claimed is:

In an antenna arrangement for a vehicle, a whip antenna having its lowerend rigidly and insulatedly secured to said vehicle, the upper end ofsaid antenna normally extending freely and substantially verticallytherefrom, an enlargement at the upper end of said antenna, a retainingmeans insulatedly secured on said vehicle, an oblique slot formed insaid retaining means, the outer portion of said slot formed to receive aportion of said antenna and the inner portion of said slot beingenlarged thereover to receive the enlarged portion of the end of saidantenna, said antenna being adapted to be flexed by moving said free enddownwardly to releasably engage said enlarged portion thereof in theenlarged portion of said slot and to be maintained thereby in bowedfixed relationship with said vehicle, said retaining means being securedon said vehicle at a point spaced horizontally from and vertically abovethe fixed lower end of said antenna but separated therefrom a distancesubstantially less than the length of said antenna, said antennamaintaining a substantial clearance from said vehicle throughout thegreater part of the length of said antenna.

CHAS. W. THOMAS. WILLIAM A. ROBINSON.

